1. Field of the Invention
The present invention relates to a sheet feeding apparatus for feeding sheets, one by one, from a stack of sheets.
2. Description of the Related Art
Sheet feeding apparatus are employed to feed sheets, one by one, from a stack of sheets such as photographic films stored in a supply magazine in order to supply the sheets to an exposure device, a developing device, or the like.
Such a sheet feeding apparatus generally has a plurality of suction cups that are pressed against a sheet to attract the sheet under a vacuum that is developed in the suction cups by a vacuum generator. When the suction cups are pressed against the sheet, however, the sheet tends to adhere to an underlying sheet. Therefore, a plurality of sheets are liable to be fed simultaneously from the supply magazine by the suction cups.
Various proposals have heretofore been made to prevent a plurality of sheets from being simultaneously fed by the suction cups of a sheet feeding apparatus. For example, Japanese laid-open utility model publication No. 61-80736 discloses a sheet feeding apparatus having two suction cups that are swingable in respective opposite directions to each other. When a sheet is attracted by the suction cups, the suction cups are swung to cause the attracted sheet to flex so that its central area is lifted or lowered, thereby separating any underlying sheet or sheets that may have stuck to the attracted sheet.
Since the two suction cups are angularly movable in the respective opposite directions, the sheet attracted to the suction cups is flexed into a relatively large curvature when the suction cups are swung. Consequently, when the attracted sheet is flexed, any underlying sheet or sheets that may have stuck to the attracted sheet often tend to flex with the attracted sheet, and remain stuck to the attracted sheet. The proposed sheet feeding apparatus thus fails to reliably prevent a plurality of sheets from being fed simultaneously from a supply magazine by the suction cups.